Line Voltage Interface for Automation Systems

ABSTRACT

An integrated PCB-based solid state line voltage interface for use in automated control system applications. Relays connect various functional loads to the line level source in response to input from a controller unit. Switches enable a user to override the controller unit, and manually control the connection of the functional loads. An alternative embodiment of the present invention further includes limit switches. The compact nature of the device facilitates ease of installation, mounting of multiple units in the same space, and mounting in various specialized locations as desired.

TECHNICAL FIELD

The present invention relates to the field of automation. Morespecifically, the present invention relates to the field of automationsystems. More specifically, the invention relates to interfacing betweenautomated control units, power sources, and two-speed or reversingelectrical motors.

BACKGROUND ART

Automation systems employ controller devices such as microprocessors,computers, and programmable logic controllers (PLC's), to controlmachinery, equipment, and processes.

These systems may control various equipment including fans, dampers,valves, vents, shade, and other equipment. Typically, automatedcontroller units are used to read a set of digital and/or analog inputs,apply a set of logic statements, and then generate a set of low voltage(50 volt or less) analog and/or digital output signals. These outputsignals are transferred from the automated control system to eitheradditional low voltage interface relays or pilot relays, that are thenoperative of the final power relays. The power relays finally engage therelevant line voltage loads, or electrical motors. These existing lowvoltage pilot relays or interface devices may or may not have integraloverride switches, but are not capable of transferring the full motorload.

Automation interfacing of reversing or two-speed motors also requiresadditional relays, wiring, and override switches which are usuallycustom built from individual electrical components. The sheer volume ofcomponents required often necessitates that large or multiple electricalboxes be utilized. Such a bulky arrangement is not conducive to mountingin tight or compact spaces. Additionally, in some situations it may bedesirable to locate the reversing motor interface so as to facilitatethe electrical installations (e.g. locating the interface next to thecontroller versus next to motor). The complicated and non-compact mannerin which present art relay/switch systems are built for automationinterfacing inhibits one's ability to locate the components and wiringin the most cost-effective, compact, and desirable configuration.

Therefore, there is a need for an integrated device for automationinterfacing of reversing or 2-speed motor applications. Such anintegrated device would incorporate relays and switches in a single,compact, easily installed interface. Such a device would facilitateautomatic control of the line voltage load by a controller unit, as wellas enabling manual override and control for special situations.

DISCLOSURE OF THE INVENTION

The present invention is drawn to an integrated solid state line voltageinterface for use in automated control system applications. Theinterface is situated between a controller, a power source, and a load.It is composed of a printed circuit board having relays, switches, andindicator lights mounted thereto. The relays connect various functionalloads to the power source in response to input from a controller unit.The switches enable a user to override the controller unit, and manuallycontrol the connection of the functional loads. In various embodimentsof the invention, the switches are directly interposed between the loadand the source, bypassing any relays, and thus facilitating directcontrol of the actual connection between the load and the source. Analternative embodiment of the present invention includes limit switches,which are useful in preventing excessive travel in applications havingdefined directional limits (e.g. windows, shades, etc). An alternativeembodiment of the invention further includes a time delay which delaysthe connection of the load. This is useful in applications involving areversing motor to allow the motor time to wind down before changingdirection.

The compact nature of the present invention offers significantadvantages over prior art methods of installation. The compact devicepresently disclosed integrates required components, is simpler toinstall, facilitates mounting of multiple units in the same space, andis more easily mounted in various locations as desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a line voltage interface in accordancewith an embodiment of the present invention.

FIG. 2 is a circuit diagram of a line voltage interface in accordancewith an alternative embodiment of the present invention.

FIG. 3 is a circuit diagram of a line voltage interface in accordancewith an alternative embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention is drawn to an integrated solid state line voltageinterface for use in automated control applications. The presentinvention replaces separate relays and switches and their associatedwiring by combining these components into a compact integrated devicethat is easy to install.

FIG. 1 illustrates a circuit diagram of a line voltage interface 100 forinterfacing between an automated controller unit, a power source, and atwo-speed motor, in accordance with an embodiment of the presentinvention. Interface 100 receives Function A and Function B signals atterminals 10 and 15 from a controller unit (not shown). These signalscorrespond to the low speed and high speed of a two-speed motor (notshown), which may effect such operations as the cooling stages of aclimate controlled building. The relays are circuited such that bothFunction A relay 20 and Function B relay 25 have their normally closedpoles connected, and fed line voltage. The common poles of both FunctionA relay 20 and Function B relay 25 are connected. The normally open poleof Function A relay is circuited to Function A motor load terminal 30;the normally open pole of Function B relay 25 is circuited to Function Bmotor load terminal 35. When no signal is present, the Function A relay20 and Function B relay 25 are normally closed, thus preventing eitherload circuit from being made. When a Function A signal is received atterminal 10 (with no Function B signal present), indicator 17 (e.g. anLED) turns on, and the Function A relay 20 is energized, therebychanging from a normally closed to normally open state. This connectsthe Function A load at terminal 30 to the source. Likewise, when aFunction B signal is received at terminal 15 (with no Function A signalpresent), indicator 18 turns on, and the Function B relay 25 isenergized and changes to the open state, thus connecting the Function Bload at terminal 35 to the source. In the event that the interface 100receives simultaneous signals for Function A and Function B, then bothrelays 20 and 25 are energized and change to the open state, whichcauses the Function A and B loads to connect to each other. The resultis that neither load connects to the source, which prevents damage thatmight otherwise occur as a result of receiving simultaneous andconflicting signals.

Switch 40 affects the controlling input for the interface 100. Whenswitch 40 is in the auto position, the connection of the Function A andB loads to the source is determined by the controller unit (not shown)as described above. When switch 40 is in the off position, no connectionof the loads is possible. When switch 40 is in the manual position, thenthe connection of the loads is determined by the position of switch 45,Switch 45 has positions for connecting the Function A and B loads, aswell as an off position. Together, switches 40 and 45 enable a user tooverride the controller unit and manually control the connection of theloads to the source. Because switches 40 and 45 are directly interposedbetween the loads and the source, this configuration allows a user todirectly switch the actual functional load, and is especially useful inthe event the controller unit becomes inoperative.

The circuit of interface 100 as disclosed may be embodied in a printedcircuit board having the aforementioned solid state components mountedthereto. In this manner, interface 100 is constructed to be a singleunit that may be easily installed in a desirable manlier.

The interface 100 of the invention has been described with reference toa two-speed motor, such that Function A and Function B loads correspondto the two speeds of a two-speed motor. However, it is recognized thatthe Function A and Function B loads may correspond to alternatives suchas forward and reverse directions of a reversing motor.

FIG. 2 illustrates a circuit diagram of a line voltage interface 200 forinterfacing between an automated controller unit, a power source, and atwo-speed motor, in accordance with an alternative embodiment of thepresent invention. Interface 200 receives Function A and Function Bsignals at terminals 110 and 115 from a controller unit (not shown).These signals correspond to the two speeds of a two-speed motor (notshown). The relays are circuited so that the common pole of Function Brelay 125 is fed line voltage. The normally closed pole of Function Brelay 125 is connected to the common pole of Function A relay 120. Thenormally open pole of Function A relay is circuited to Function A motorload terminal 130; the normally open pole of Function B relay 125 iscircuited to Function B motor load terminal 135. When no signal ispresent, the Function A relay 20 and Function B relay 25 are normallyclosed. When a Function A signal is received at terminal 110 (with noFunction B signal present), indicator 117 turns on, and the Function Arelay 120 is energized and changes from a closed to open state. Thisconnects the Function A load at terminal 30 to the source. Likewise,when a Function B signal is received at terminal 115 (with no Function Bsignal present), indicator 118 turns on, and the Function B relay 125 isenergized and changes to the open state, thus connecting the Function Bload at terminal 135 to the switched source. In the event that theinterface 200 receives signals for both Function A and Function B, thenboth relays 120 and 125 will change to the open state, which results inconnection of the Function B load to the source, while the Function Aload is not connected. This arrangement is useful in particularapplications where the Function A and Function B signals are staged orsequentially supplied and maintained by the controller unit, as itmaintains Function B when receiving simultaneous signals for bothFunction A and B. Thus, the interface 200 is especially applicable tomechanisms such as multi-speed fans, and stepped cooling and heatingmechanisms.

Switch 140 affects the controlling input for the interface 200. Whenswitch 140 is in the auto position, the connection of the Function A andB loads to the source is determined by the controller unit (not shown)as described above. When switch 140 is in the off position, noconnection of the loads is possible. When switch 140 is in the manualposition, then the connection of the loads is determined by the positionof switch 145. Switch 145 has positions for connecting the Function Aand B loads, as well as an off position. Switches 140 and 145 aredirectly interposed between the loads and the source, thereby allowing auser to directly switch the actual functional loads.

The interface 200 of the invention has been described with reference toa two-speed motor, such that Function A and Function B loads correspondto the two speeds of a two-speed motor. However, it is recognized thatthe Function A and Function B loads may correspond to alternatives suchas forward and reverse directions of a reversing motor.

FIG. 3 illustrates a circuit diagram of a line voltage interface 300 forinterfacing between an automated controller unit, a power source, and areversing motor, in accordance with an alternative embodiment of thepresent invention. Interface 300 receives open and close signals atterminals 210 and 215 from a controller unit (not shown). These signalscorrespond to the forward and reverse directions of a reversing motor(not shown). The relays are circuited such that both Close relay 225 andOpen relay 220 have their normally closed poles connected, and fed linevoltage. The common poles of both Open relay 220 and Close relay 225 areconnected together. The normally open pole of Open relay 220 iscircuited to the Open motor load terminal 230; the normally open pole ofClose relay 225 is circuited to the Close motor load terminal 235. Whenan open signal is received at terminal 210, the open relay 220 isenergized and changes from a closed to open state. This connects theopen load at terminal 230 to the source. Likewise, when a close signalis received at terminal 215, close relay 225 is energized and changes tothe open state, thus connecting the close load at terminal 235 to theline source. In the event that the interface 300 receives simultaneoussignals for open and close, then both relays 220 and 225 are energizedand change to the open state, which causes the open and close loads toconnect to each other. The result is that neither load connects to thesource.

Time delays 240 and 245 delay the energization of relays 220 and 225,respectively. This feature is particularly useful when the Function Aand B loads are the forward and reverse directions of a reversingelectrical motor. The delays prevent immediate changes from onedirection to the other, allowing time for the motor to wind down. Thisprevents damage to the motor that could result from immediate changes indirection.

Limit switches (not shown), as are known in the art, are connected toterminals 260, and function to limit the activation of relays 220 and225. This is useful for limiting the range of operation of the loads,and may prevent damage that would otherwise result from exceeding therange of operation.

Switch 250 affects the controlling input for the interface 300. Whenswitch 250 is in the auto position, the connection of the relays 220 and225 are fed by the controller unit (not shown) as described above. Whenswitch 250 is in the off position, the relays cannot be energized. Whenswitch 250 is in the manual position, then the energization of therelays is determined by the position of switch 255. Switch 255 haspositions for energizing each of the relays, as well as an off position.

Interface 300 as illustrated in FIG. 3 is shown as having 24V powersupplied to operate the coils of the relays and to operate the timedelay and limit switches. The loads are shown as connecting to either24V or 120V AC power (120V AC being conventional line level voltage inthe United States). The voltages shown are conventional in the art, andare merely representative of a possible configuration for the interface.It is recognized that other voltages may be applied, this beingcontemplated within the scope of the present invention.

The aforementioned embodiments of the invention each may be constructedby mounting the relevant solid state components to a printed circuitboard having a circuit design as disclosed. By combining these severalcomponents into a single integrated device, the required amount ofwiring is reduced, and ease of installation is greatly improved. Becausethe device is compact, several units may be easily mounted in a singleelectrical box, which is in contrast to conventional methods that entailmounting separate components in multiple electrical boxes. Theinstallation of multiple units in a single space also facilitates easyand simultaneous access to multiple interfaces.

Furthermore, the compact nature of the device of the present inventionmeans that it is easily mounted in various locations for convenience,aesthetics, cost-efficient use of materials, or as otherwise desirable.For example, it may be desirable to locate the interface in closeproximity to the line level load (e.g. a reversing motor) in order tofacilitate intuitive and direct control when needed. The integrateddevice of the present invention can be easily mounted in such a locationwhile occupying a minimum of space.

Information as herein shown and described in detail is fully capable ofattaining the above-described object of the invention, and is, thus,representative of the subject matter which is broadly contemplated bythe present invention. The scope of the present invention fullyencompasses other embodiments which may become obvious to those skilledin the art, and is to be limited, accordingly, by nothing other than theappended claims, in which reference to an element in the singular is notintended to mean “one and only one” unless explicitly so stated, butrather “one or more.”

All structural and functional equivalents to and combinations of theelements of the above-described preferred embodiment and additionalembodiments that are known to those of ordinary skill in the art arehereby expressly incorporated by reference and are intended to beencompassed by the present claims. However, it should be readilyapparent to those of ordinary skill in the art that various changes andmodifications in form, apparatus material, and fabrication materialdetail may be made without departing from the spirit and scope of theinvention as set forth in the appended claims.

Moreover, no requirement exists for a device or method to address eachand every problem sought to be resolved by the present invention, forsuch to be encompassed by the present claims. Furthermore, no element,component, or method step in the present disclosure is intended to bededicated to the public regardless of whether the element, component, ormethod step is explicitly recited in the claims. No claim herein is tobe construed under the provisions of 35 U.S.C. §112, sixth paragraph,unless the element is expressly recited using the phrase “means for.”

INDUSTRIAL APPLICABILITY

The present invention is industrially applicable to automated controlsystems.

1. An interface for interfacing between an automated controller unit, apower source, and a reversing motor, said interface having at least onerelay and at least one switch, said relay connecting said motor to saidpower source, and said switch facilitating manual override of saidrelay.
 2. An interface as in claim 1, wherein said interface comprises aprinted circuit board for coupling solid state components.
 3. Aninterface as in claim 2, further including a second switch forcontrolling speed and direction of said motor.
 4. An interface as inclaim 3, wherein said second switch controls power directly applied tosaid reversing motor.